1. Field of the Invention
The present invention concerns a process and a die for the manufacture of lined panels for the trimming of interiors of motor vehicles in general. The covering for motor vehicles interiors is normally obtained by using lined panels generally consisting of a supporting plate made of thermoplastic material coupled with a covering. Said covering is usually constituted by areas of fabric placed adjacent to areas of calendered plastic, or imitation leather, along junction lines and/or superimposition lines. The arrangement of the fabric portions varies according to the panel required. In particular, the fabric portion may be placed inside the imitation leather portion, thus forming a so-called "medallion", i.e. an area of fabric completely surrounded by the calendered plastic portion of the covering, or, alternatively, it may extend from the junction line with the imitation leather portion as far as the edges of the panel itself. In the first case the junction and/or superimposition line is closed on itself, in the second case it is an open line.
2. Description of the Prior Art
The die to produce lined panels is usually formed by two half-dies shaped in a complementary way according to the desired profile of the panel. During molding a preheated supporting plate is positioned on the lower half-die, then the upper half-die is closed bringing the covering, previously stretched on a positioning frame, in contact with the heated plate, thus fixing the covering onto the plate simultaneously with the panel shaping operation.
The main problem of this coupling technique by molding with simultaneous shaping involves the need of exactly positioning the covering with respect to the panel.
In fact the different portions of the covering, i.e. fabric and imitation leather, must occupy predetermined areas on the finished panel, and just on said areas they have to be exactly positioned during molding not to negatively affect the final aesthetics of the panel.
Moreover, in case it is foreseen to manufacture a panel presenting the so-called shadow effect, namely a panel in which said junction and/or superimposition line is housed inside appropriate slots provided during molding on the supporting plate, the positioning of said junction line and therefore of the covering areas with respect to the die must be even more precise. In fact an uncorrect position of the junction and/or superimposition line with respect to the slot would much more negatively affect the final aesthetics of the panel than in the previous case.
To ensure the necessary exact positioning of the single portions of covering, the normally used techniques foresee, for example, pressing members such as dandy rolls or similar pieces of die movable with respect to the half-die housing them. Said members may be present on one or both the half-dies and are generally provided in correspondence with the junction and/or superimposition lines of the covering, in a way that, at the beginning of the molding stage, they bring said lines in contact with the supporting plate, before the panel final molding.
The use of such pressing members, however, involves problems due to the fact that, by engraving the softened supporting plate, they cause thinnnings on it which sometimes may be considerable as to cause the final panel to be rejected.